Preserving wood.



- s ATa-s PATENT or rrca.

W LTER BUEHLER, or MINNIEAIOLIS,MINNESOTA, issrenor. or ON-EJIALF To GEORGE w.

BESTOR, OF MINNEAPOLIS, MINNESOTA. e rnnsxnymo woon.

Continuation of application mu m. 418,001, filed-February 27, 190:. a uarium445,639.

Toallwhomi tmayconcenif v Be it known; that I, WALTER Bunnum, a

citizen of the United States, and resident of Minneapolis, Hennepin county, Minnesota, 'have invented certain new and useful In1 provements in the Art of Preserving Wood, of which the following is a full, true, clear, and exact description, such as-will-enable others to practice the same. I

My inventionreljates to the art of preserv-.

ing wood and has special reference to im-.

provements in'the art of drying or seasonin and preserving green-and partially seasoned 'wo'od, witha view to increasing-the efl'ectual strength thereof forst-ructural purposes and preventing decay and the ravages of insects and worms when the wood is-submerged in water, buried in the ground or exposed to the weather;

Further, my'invention is chiefly concerned with the effective impregnation of green-and partially seasoned wood with bituminous iquids. andfdistillates of bituminous substances commonly known as non-aqueous liquids that are substantially free from we er, such as creosote oil. Green -wood is strengthened by the removal ofwat'er and wa ery substances from its cells, pores and fiber, part-icularly the latter, "an :When .freed from water may be impregnated-with reserval ive liquid of the class named wit outloss of strength, for the reasonthat the oil, unlike water, does not penetrate the wood filter.

Such oil when uniformly distributed upon. the walls of the cells and poresofthe wood 1 excludes moisture and retards and practically prevents decomposition o r rottin of the wood. It also preserves the. woo against the-attack of landand marine insects,s uch as teredo, hmnoriavandtermites. Cert/am uses necessitate the complete sat- :uration or permeation of wood with a nonwalls of the cells and aqueous preservative, in order that moisture shall be wholly excluded, to prevent them]- ternate swelling and shrinking of the wood when in use; but for most uses, I'findthat partial saturation suiiices, providedthe'pre- Servative is distributed infil'm form upon the wood.

The object ofmy invention is to enable the effectual seasoning of green wood and partially seasoned .wood within a short period of time and without'i'reakening the wood pores throughout thev Specification of Letters Patent. l Patented ls'ebtgggl, 1:908? 1,.

I l'pplication'filod 19:.

liiber, and, further, to enable the complete and thorough inlprelgnationof wood with preservative liqui within alike. short riod and at lessexpense thanhitherto,

tain theseobjects I first extract or drive out the liquid matters in the wood by vaporizing the samewithin the wood. I do this by inimersing the wood in a bath of nomaqueous preservative liquid and gradually raising the temperature 0 the liquid and wood 'to a temperature which is hlgher than the vaporizui In t is manner I efi'ectually and quickly oint of the moisture, etc., the wood.

season the wood, pre aratoryto the next step of the process. en practically all of the liquid matters and air have been excludedfrom the wood and referably while the-wood is still in the bath, Ihorce the requisite quantity of the of h uid to pressure, if need be, and varyin the c arge or quantity driven into thewo'o according to different requirements or specifications.

After charging the wood with reservative iutothe outer cells and pores. o the wood. subjecting the body liquid in this manner, I remove it from the bath, t'.e-., drain off thesurplus'liquid, and

subject it to external ressu re of non-aqueous as to drive the liqui further into the wood. Ipreier to employ air for this purpose and'by means thereo home, that is, distri ute the li uid uniformly upon the cell- Walls throug out the piece of wood. A predetermined air pressure is. preferably continued until the wood refuses to take up further quantities of air.

My invention as above described, together With certain incidental steps thereof, will be more readily understood by-reference to the accompanying drawings, forming a part of this s ecification and m which I have illustrate the apparatus'that I have found tobe best adapted to the purposes of the invert-- tion'.

scope of my preserving :wood This cylinder s large 'enoughjtocontain a car or truck, 3, ands,

loadof med, 4. A large door or head,?5,

.tightly closesthe end of thecylinder, the

so to s eak, force the charge I shall describe the apparatus and packing bein such asto permit a high pressure of liqui or airto bemaintaineu in the Y "cylinder. LA heating coil, 6, in the lower part of the cylinder and su sure steam from-the bo' er, 7, is used to eat the contents of the cylinder. 8 is the steam regulating valve. A reservoir, '9, contains the preserving liquid. The capacity of. the reservoir, 9,'considerabl excee cylinlder, so that the atter may be comp e s that'of the teg filled with liquid, as hereinafter mentione 4 9 represents a gage for automatically reg- I istering the supply of liquid inand from the reservoir. --Tlns 18 used in determining the volume of liquid in'ected into the wood in the manner herein ter described.

I 10 is the liquid main or conduit. A pi e 1 1, having a'valv'e,12, joins the mainto t e lowest part of the cyhnder andis used in draining the cylinder.

13 is the mam liquid connection of. the cylinder and contains a valve, 14.

, 11 P ma, .5, is interposed between the pipes, 10 'and 13,

- and is adapted to forcibly transfer the liquid i rom the reservoir to the cylinder and create a'high pressure of liquid in the latter.

16 is a cut-off valve between the reservoir and the pump.

A pressure gage, 17, at the top of the cyl inder serves to indicate the pressure therein at different stages of the process. At the high point of the cylinder is a blow-ofi' connection, 18, equipped with valves 19, 19' and 19", the latter'hein an'automatic, we h ted valve adapted to be opened by internal pressure of about one to ve pounds.-

.' 20 represents an air pump or other source of compressed air-joined to the cylinder by the ipe, 21, having valve, 22.

pon arrival of a car 'of wood at the c linder the door thereof is swung open an the car is placed in the cylinder, after which the door is closed and made tight. Meantime all the valves have been closed. Thereupon I open the valves 16, 14 and 19 and, starting' 15, fill thecylinder with preservthe 1pum ing 'qui from the reservoir. As the liquidenters the cylinder it expels the air therefrom through the blow-off or waste pipe 18 and the z'gutomaticvalve 19", the valve 19, as stated, a

then- 0 en. When the cylinder is near y full of hguid the'valve 14 is closedto trap the same in the cylinder and steam is admitted to the heating coil, 6. In this man ner the wood is completely immersed in the liquid or oil and the apparatus is put in readiness for the next step of the rocess.

' This next step consists in gradually eating w the contents of the cylinder and holding thesame fora time at atemperature exceeding that at which vaporization of the watery substances in the wood takes place. In'

practice- I slowly raise the temperature from thatat which the liquid entersthe cylinder to. about 220 to 250 Fahrenheit, varying the temperature according to the character lied with high res- 'bo y of heavier of the wood under treatment. The fem rature of the wood, immersed the lilrl ui or oil, is in this way increased so gradua case-hardening and without-checking or cracking, such effects beingavoided by the,

slow seasoning of thewood within the envel V oping. liquid, which talics the 'place -of. .th'ewater in the surface at this high temperature the moisture in the cells and pores of thewocd and also that con- 30 tained in the wood fiber rapidly volatilized and expanding, naturally forces its way to;

the sur ace of the wood. It carries with it most of the sa and gums and also the air 'contained in t e.wood. The air and the from the wood enter the va ors on emerg' quid and being lighter,

t e surface of the li uid or 0' The vapors and gases, principle.Ii v steam, accumulate in the top of the cy uickly rise to the topof the c linder, i. a, to

dcr but do not attain a high ressure therein; the relief valve 19" pern'ntting the esca thereof at a pressure that is considerable owe-r than that of steam at the temperature of' the liquid. The low pressure at which the vapors are ermitted to escape'from the wood and the h temperature imparted to the wood. through the preserving liquid, insure the rapid or seasoning of the wood. In practice I heat the W0 in this manner, from four to eight hours and effectually empty the cells and ores of the wood and also deprive the wood ber of most of its watery content. The time varies with different woods and with the condition of the wood as to contained moisture, very green wood 'requmng more 'extended treatment than that which is partially seasoned. .A valuable result of-the closing of. the cylinder and the maintenance of pressure therein during the heating erioi is that at substantia the oil is continuously confine and the 'loss' of even the most volatile constituents .therco'f is prevented. It follows that the specific I gravity of the 1preserving liquid ismaintained process, makinghit possible to accurately fix and measure t e quantity and weight of e lained hereinafter.

' onsiderable quantities of steam, sap, m

quid injected into the wood, as more fully' and'other impurities collect inthe top 0 the en the cylinder beopen the v ve 115 y a constant throughout the that I the wood takes'lon auniform; heat, without pores" of the wood and keelps thelatter open.- The redetermined" big temperature, when reac ed, is 'main-n tallied until ractically'all of the moisture and air have een driven from the wood, i.e.,

55 u tus, 20; the valve, 12, in such case entrance of a quantityof relatively cool oil 'causes a drop to this end I again st-a'rtthe pump, 15, and

, .pounds and malntain this wood and the length of the sticks under upon the. liquid rapidly forces it mto the Indicator, 9, of the reservoir before pressure rect to the reservoir main, 10.,

, other dry gas atapproximate y atmospheric per remaining the cells of t e wood, Thiscooling and condensation maybe and'is prefera'bly augmented by cutting off he steam k from thecoil, 6, "and-perrr'tting tnecylinder the'heat"is -.cut off, the heavy oil, to a consid- -hereinafter.

pores'and cells, because of the hereinbefore the source, 20, at apressure usually approxitemperature throughout the body of oil and the wood; Ihis results in the condensation of the minute uantities of va-' to cool for aspace of time before proceeding U -with the next step of the process. Duringthe time that the cylinder is heated and after erable extent, replaces the moisturewhich driven from the wood,- particularly in the surface or outermost cells and oresthereof. Thus the surface ores, are c osed by the heavy oil; the rare action of the contents of the interior cells tendin also to increase the quantitv of liquid absoroed by the wood. In cases where light treatment is sufficient and in the case of some very orous woods this initial charge of liquid su ces, and the wood may at once be subjected toair pressure to disseminate-the oil in the wood, as explained But in most cases it is necessary to inject a further quantity of liquid and raise the liquid pressure to from 125 to 180 r'essure'until a suflicient quantity of the iquid has been taken up by the wood. In ractice the pressure is varied according to ilhe density of the treatment, long pieces of wood ordinarily requiring the higher pressure. The pressure wood and the penetration is augmented rather than; resisted by the contents of the mentioned vacuums therein, which vacuums, 1t Wlll be noted, increase steadily as the temperature falls; A reading is taken from thes put upon the contents of the cylinder and the movement of the indicator is watched during the operation of the pressure pump. Such movement, obviously, measures the' qpantity of oil which is being injected into t e timber and when the re uisite quantity has been thus lodged therein the pump is stopped. Thereuponthe pump is reversed and the surplus or residue of liquid is withdrawnfrom the cylinder.. Tl'llS operation may if desired, be supplemented by the admission of compressed air from theap araem opened to bypass a portion of the liquid di After emptying the cylinder the valves, 12 and 14, are closed and the process is proceeded with as follows: Com' ressed air, or

temperature, 1s supplied to the cylinder from mating 25 pounds," This non-aqueous gas l 1isina enters thepores. and cells of the. wood and,

wood,'forming thm films uponjthe walls of a even the innermost cells. ThiZactua-Ldis tzibution' ofjthe oil," as to quan tity', .":is?of course dependent Lu on the volume ofv the charge, but itiisnotlceable that evenin-the case of a small charge of liquid a deep and 1 I effectual penetration results from the ,use of the cool compressedgas as described'. Apv V 3' so paratus which is. adapted to icontinuous supply the air at-stated pressure may be use but I have found it most convenient to furnish the'air intermittently, by the occasionalopenmg and closing of the valve, 22; When, after the cylinder has been charged atmaximum pressure, the indicator or gage,.17, remains stationary, it shows that a condition ofgaseou's equilibrium has been established in the wood, '11. 'e., that the oil and air have enetratedinto the innermost parts thereof.

ractical or operating sense marks the end of pressure may be relieved, the door, 5, opened and the car removed from the cylinder. Upon relief of pressure, as by removal of the wood from the cylinder, the gas under ressure therein quietly expands and flows om the wood until atmospheric pressure is established. The'inject1on of the charge of liquid, as above described, may be hastened by the employment of greater air ressure the process and at such time the" but I prefer the lower pressure name( for the reason that air or gas under such pressure leaves the wood without violence and withmoval of the wood from the cylinder, or immediately receding its removal, the quan- 'ty e'ected could not easily be determined and the actual quantity remaining inthe wood would therefore be unknown. It is therefore obvious that my process possesses.

andclosing the pores thereof. i It is usually 'ste s com r sing the unnecessary to subject the heavy liquidto' pressure and it may be drawn off at once.

As will. appear from the foregoing, the rocess are subject to sue ,modi cationas t lose-' who are skilled in T the practice find necessary to obtain the requisite 'or desired results. For thesereasons I do not confine my invention to the specific acts or steps as herein'desoribed-.-;

This ap .lication is a substitute for my re-' vious appication, Serial No;- 4 18,094, fled .VFebru'ary'fi27, 1-908; allowed April 7 190.8;

'- servative liquid, then draining ofi the sur- {formally abandoned July 18, 1908; I

H avin'ge thus 'described "my invention I claim as new and desire to secureby Letters Patent": xv f -1 The herein'describedimprovement in theflart of preservingwood, that consists in immersing wood in a bod of non-aqueous reservative liquidin a c osed vessel, then eating the same sufiiciently to ex and the gaseous and waterycontents of t e wood' and. thus cause. their expulsion therefrom,

partiallycharging-the wood with said preplus liquid, then immersing the wood in a ody of low-temperature com ressed gas until'substantial' gaseous equiligriuni'is' established in the wood and then relieving the v gaseous pressure, substantially as described.

2.The herein described improvement in the art of preserving wood, that consists in unmersing wood in a bod 'of non-aqueous preservative hquid in a c osed vessel, then eating the same sufiiciently to expel the gaseous and watery contents of the wood,

'' then exertin pressure upon said confined body of liqui until the wood is sufiiciently impregnated therewith, then removing the surplus liquid, then immersing the-wood in low-temperature, compressed gas and thereby disseminating the liquid in the wood and then releasing the pressure and permitting the ex- 0683 gas to flow from the wood, substantially as described.

w 3. The herein described improvement in the 'art. of preserving wood, that consists in imthewoo in'a low-temperature compresse v mersing wood in a body of non-aqueous'preservative liquid in a closed vessel, then heating the same suflicientl to expel the gaseous and watery contents 0 the wood, then withdrawing the watery accumulation from the surface of said body of liquid, then again confining -the body of liqui and exerting pressure thereon until the wood sufficiently charged with said liquid, then releasingand removix' the surplus liquid, then immers' "1 lessens-1 stantially as described. .4. The herein describedimprovement in the art of preserving'wo'od that consists of as i immersing wood in a bod ,of non-aqueous. preservative'liquid, then eating the same sufficiently to expel the gaseous and wate wood by exerting pressure upon said liquid,

then draining the surplus liquid from the surface of the wood', then immersing the wood in low-temperature compressed 'gas until sub? stantial gaseou's'equilibrium is establishedin 7 5 the wood, and then permitting the excess of to flow from the wood, substantially as v escribed; I

5 Theherein described improvement in the art ofpreserving wood, that consists iIi immersing wood in a bod of hon-aqueous preservative liquid in a c osed vessel, then eating the same until the gaseous and watery contents of the wood are substan-' tially expelled, then reducin the temperature of'said li uid and woo and exerting 7 pressure upon t e liquid to force a qliliantity thereof into the wood, then relieving t e pressure and removing the surplus liquid from the wood, then immersing the wood in low so temperature compressed gas, thereby' dissermnating the charge of liquid throughout the wood and then permitting the excess as to fiow from the wood, substantially as esoribed. r

6. The herein described improvement in the art of preserving wood that consists in,

immersing. wood a bod? of nona ueous preservative liquid in a c osedvesse then heating the same sufficiently to expel the gaseous and watery contents of the wood,

then exerting further pressure upon the com fined body'of liquid until'the wood is partia'lly charged therewith, then draining off the surplus liquid, then immersing the wood' 106 in low-temperature c'o'm ressed gas until substantial gaseous e'qu 'brium 1s established in the wood,-then releasing the gas and then coating the surface of the wood with material which is impervious to mois- 110 gas until substantial gaseous equilibrium is to I established inithe wood and then permittmg the excess gas to flow. from the wood sub:

contents of the wood, then cooling the woo i 'then forcing a quantity of said liquid into the 70.; 

